The present invention relates to a method for controlling an adjusting movement of a vehicle closing element to be closed in a manner actuated by an external force and also to a capacitive anti-trap system.
With vehicle closing elements that can be adjusted increasingly in a manner actuated by an external force, in particular in a motor-driven manner, there is a considerable risk as the respective vehicle closing element closes that, for example, a body part of a person standing close to the vehicle will be trapped, which may lead to considerable injuries. A vehicle closing element of this type may be, for example, a side door, a tailgate lid, a window pane, or a sunroof of a motor vehicle.
By way of example, US 2007/0035156 A1 describes an anti-trap system in which two electrode arrangements each having a transmitter electrode and a receiver electrode are provided on mutually opposed longitudinal-side closing edges of a vehicle tailgate lid. The individual electrode pairs each define a monitoring region on a closing edge of the tailgate lid, in which an obstacle in the path of adjustment of the closing tailgate lid can be detected. Here, the two electrode pairs are each activated and evaluated separately. An electronic evaluation unit of the anti-trap system of US 2007/0035156 A1 thus always receives at least two signals, on the basis of which the electronic evaluation unit can determine the presence of an obstacle in one or other of the monitoring regions.
With capacitive anti-trap systems on vehicles, in particular on motor vehicles, known per se to a large extent, an obstacle in the path of adjustment of a vehicle closing element to be closed in a motor-driven manner is detected contactlessly by a changing electric capacitance and prevents an obstacle from being trapped between the closing vehicle closing element and a vehicle structure in the region of a body opening that is to be closed by the vehicle closing element in a closed position. Compared with purely tactile anti-trap systems, anti-trap systems with capacitive detection provide the advantage that a potential obstacle can be determined already before contact with the vehicle closing element or already shortly thereafter without having to exert a specific force on the sensors of the anti-trap system in order to trigger the system and stop and/or reverse the adjusting movement of the vehicle closing element.
With capacitive anti-trap systems that form the basis of the present invention, use is made of the fact that, in an electrode arrangement of the anti-trap system consisting of at least one transmitter electrode and one receiver electrode, a signal characteristic for the presence of an obstacle can be received at the receiver electrode when the transmitter electrode is activated with electric alternating current. By activating the transmitter electrode with alternating current, an electric field is produced, which is influenced by an obstacle in such a way that an electric capacitance is changed in a manner that can be measured. This measurable change of the electric capacitance can be measured at the receiver electrode, which is arranged at a distance from the transmitter electrode, and can be evaluated on the basis of a signal received by the receiver electrode, usually a voltage signal, in order to trigger the anti-trap system and in order to influence the adjusting movement of the vehicle closing element.
The adjustment of a vehicle closing element actuated by an external force not only poses an increased risk of injury by a possible entrapment. There is generally also a considerable injury risk by a locking part provided on a vehicle closing element, such as a lock. Locking parts of this type, by means of which the vehicle closing element is locked to the vehicle structure in the closed position, protrude in part on the vehicle closing element by a number of centimeters, such that collision of the locking part specifically and a person during adjustment of the vehicle closing element is likely. In addition, such locking parts are usually very heavy and are made largely from metal, such that a collision is thus particularly painful for a person.